Factorized Precoder Structure for MU-MIMO Feedback Overhead
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Solution Overview
Problem
Current multi-user MIMO systems face challenges in accurately estimating and reducing interference between co-scheduled users due to limited CSI feedback, leading to poor performance.
Innovation Solution
A factorized precoder structure for multi-beam precoder codebooks is introduced, which selects a subset of orthogonal beams and obtains their power levels and phases to generate parameters, reducing feedback overhead while enhancing MIMO performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If limited CSI feedback is used in multi-user MIMO systems, then feedback overhead is reduced, but interference estimation and reduction performance deteriorates
Solution Approach 1:
The precoder matrix is segmented into multiple factors (e.g., wideband precoder matrix and subband precoder matrix), allowing different levels of feedback granularity. This segmentation enables the system to provide detailed interference estimation information where needed while reducing overall feedback overhead by not requiring full precision across all frequency bands.
Solution Approach 2:
The feedback mechanism is made dynamic by adapting the precoder matrix structure to different frequency bands and channel conditions. The system dynamically selects between wideband and subband precoding based on channel variability, providing high measurement precision when channels are frequency-selective while reducing feedback overhead when channels are relatively flat across bands.
2Reliability
If rich precoder feedback is provided to improve MU-MIMO performance, then interference reduction capability is enhanced, but feedback overhead increases
Solution Approach 1:
The precoder feedback is segmented into essential components (wideband precoder matrix and subband precoder matrix) that capture the most critical channel characteristics. This segmentation provides rich precoder feedback for improved MU-MIMO performance and interference reduction while limiting feedback overhead by excluding redundant information.
Solution Approach 2:
The system changes parameters of the precoder matrix (such as using different codebook indices for wideband and subband precoding) to adapt to varying channel conditions. This allows rich feedback information to be provided in a compressed parameter form rather than full matrix feedback, enhancing performance while controlling overhead.
Data Source
AI summary
A method and a device for sending parameters of a precoder in a wireless communication system are disclosed. According to one aspect, the method comprises: sending, to a network node, an indication of a subset of beams selected from a plurality of orthogonal beams and an indication of power levels of the selected subset of beams, for a first frequency granularity; and sending, to the network node, an indication of phases of the selected subset of beams, for a second frequency granularity, wherein the indication of the selected beams, the indication of the power levels of the selected subset of beams and the indication of the phases of the selected subset of beams are part of the parameters of the precoder.